Objective: Psychoacoustics links the physical parameters of sound with the sensation and perception that they evoke. The Intensity, frequency and timing are three basic characteristics of sound that are considered in most psychoacoustic studies. There is no study in Iran regarding just noticeable difference (JNP) of sound intensity, frequency and time. Method: This cross-sectional analytical study was performed on 28 normal right-handed subjects (14 males and 14 females) in the age range of 18 to 30 years. The subjects were randomly selected from among people without any previous ear disease or surgery, neurological disorder, and speech, language and hearing difficulties. The JND of sound intensity relative to the stimulus level, the JND of sound frequency relative to the stimulus frequency, and the shortest sound gap detection relative to the level of stimulus intensity were measured by conducting "intensity discrimination", "frequency discrimination" and "gap detection" tests and analyzed based on ear and sex.Results: The JND of sound intensity and the shortest amount of sound gap detection improved (decreased) at higher stimulus levels in both "intensity discrimination" and "gap detection" tests. The JND of sound frequency increased as a function of frequency increments, and the ear and sex had no effect on results.Conclusion: Our results are concordant with previous studies and can be considered as a basis for proposing related research studies and can also be used in clinical evaluations of auditory disorders.